The cleaning power of UV light air purifiers
UV radiation has been used as a method of disinfection for decades, and with a long list of benefits, it’s easy to see why. Here’s everything you need to know.
First things first, what is UV?
UV (commonly called ultraviolet light) is one of the seven forms of electromagnetic radiation—energy from the sun—that is transmitted in waves at different wavelengths and frequencies. There are three types of UV radiation, classified according to their wavelength and measured in nanometers. The shorter the wavelength, the more harmful the UV radiation.
UVA (315-400 nm)
UVA is the longest wavelength, accounting for up to 95 percent of the UV radiation that reaches the earth’s surface. It penetrates through cloud cover, windows, and deep into the skin, causing aging signs (like spots and wrinkles) and even skin cancer.
UVB (280-315 nm)
UVB makes up around 5% of the suns UV rays that reach the earth’s surface. It’s not strong enough to penetrate glass but can damage the outer layers of skin and is the main cause of sunburn and skin cancers.
UVC (100-280 nm)
UVC is the shortest wavelength and most harmful of the three forms of UV. It’s not strong enough to penetrate the earth’s atmosphere in its natural form but is produced and used as a method of disinfection.
How does UVC-disinfection work?
UVC rays destroy the DNA of microorganisms, preventing them from reproducing. Lucky for us, they are completely filtered out by the earth’s atmosphere, so life—and the DNA molecules used to sustain it—can exist on earth. Manmade sources of UVC are produced and used to disinfect water, air and surfaces.
How UVC destroys DNA
When UVC light penetrates a cell, it causes new double bonds (or “dimers”) to form between the nucleotides in DNA (most commonly thymine—one of the four basic molecules making up DNA). This “dimerization” damages the nucleic acids in DNA which prevents microorganisms from infecting and reproducing. The stronger the UVC dose, the more damage occurs to the cells and the higher the mortality rate.
The benefits of UVC disinfection
- Environmentally friendly and biological
- Continuously disinfect (24 hours per day)
- Low operational costs
- Easy and flexible application
- Proven effective
How UVC is used to disinfect air
UVC radiation is commonly used in air purifiers. This is in fact the safest way to employ UVC radiation because there is no exposure to human skin or eyes. In short, ultraviolet light shines onto a catalyst in the air purifier, which converts water in the air into a form that turns molecules of pollution into more harmless substances. This process is called ‘photocatalytic oxidation’.
Using photocatalytic oxidation technology in Air Purifiers
Typical air purifiers use a filter to trap pollutants in the air. They don’t filter out all harmful substances and the filters must be cleaned regularly to ensure the machine works effectively. Air purifiers that use photocatalytic oxidation (like the i-air) completely transform the harmful substances in air, effectively destroying them. These air purifiers need two components to work:
- Two types of UV light—UVA and UVC. UVA is a pre-radiation before UVC. The combination of both types is proven to destroy more harmful bacteria and viruses compared to using just one.
- A catalyst (typically titanium dioxide) to convert harmful air substances into something less harmful.
Here’s how it works:
Step 1: UV light shines on the titanium dioxide catalyst, releasing electrons at its surface (the tiny, negatively charged particles inside atoms).
Step 2: The electrons interact with water molecules (H2O) in the air, breaking them into highly reactive, short-lived, uncharged forms of hydroxide ions called hydroxyl radicals.
Step 3: These small hydroxyl radicals then attack bigger organic (carbon-based) pollutant molecules, breaking apart their chemical bonds and turning them into harmless substances such as carbon dioxide and water. This describes the ‘oxidation’ part of photocatalytic oxidation.
Ideally, you’d want to invest in a high-capacity air purification device like the i-air, that combines the highest-grade filtration technology with the kill-strength of photocatalytic oxidation. The i-air collects even the smallest particles in its filter and neutralises 99.9999% of all microbes such as viruses, bacteria, spores and mould. This unique combination ensures the best possible air quality levels in areas of up to 500 m².
Learn more about the air purifying power of the i-air here.